The present invention relates to a surgical instrument and more particularly to an arthroscopic or endoscopic surgical instrument which may be used to remove or otherwise treat tissue.
Some surgical instruments of this type have flexible drive shafts. The flexible drive shaft includes a flexible section that is joined at each end to a rigid section or a rigid cutting tool. The flexible section is commonly a spring made of a cold-worked metal and the rigid sections are also made of metal. The parts are joined by welding. In some cases the cold-worked metal spring can lose its strength in the vicinity of the weld. Also, the spring can become distorted by the heat of the welding process. The loss of spring strength in the vicinity of the weld can cause the spring to break at unacceptably low driving torque.